package net.betou.common.security.encoder;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.commons.codec.binary.Hex;

/**
 * MD5密码加密
 * 
 * @author 叶装装
 * 
 */
public class Md5PwdEncoder implements PwdEncoder{
	public String encodePassword( String rawPass ) {
		return encodePassword( rawPass, defaultSalt );
	}

	public String encodePassword( String rawPass, String salt ) {
		String saltedPass = mergePasswordAndSalt( rawPass, salt, false );
		MessageDigest messageDigest = getMessageDigest( );
		byte [ ] digest;
		try{
			digest = messageDigest.digest( saltedPass.getBytes( "UTF-8" ) );
		}catch( UnsupportedEncodingException e ){
			throw new IllegalStateException( "UTF-8 not supported!" );
		}
		return new String( Hex.encodeHex( digest ) );
	}

	public boolean isPasswordValid( String encPass, String rawPass ) {
		return isPasswordValid( encPass, rawPass, defaultSalt );
	}

	public boolean isPasswordValid( String encPass, String rawPass, String salt ) {
		if( encPass == null ){
			return false;
		}
		String pass2 = encodePassword( rawPass, salt );
		return encPass.equals( pass2 );
	}

	protected final MessageDigest getMessageDigest( ) {
		String algorithm = "MD5";
		try{
			return MessageDigest.getInstance( algorithm );
		}catch( NoSuchAlgorithmException e ){
			throw new IllegalArgumentException( "No such algorithm [" + algorithm + "]" );
		}
	}

	/**
	 * Used by subclasses to extract the password and salt from a merged
	 * <code>String</code> created using
	 * {@link #mergePasswordAndSalt(String,Object,boolean)}.
	 * <p>
	 * The first element in the returned array is the password. The second
	 * element is the salt. The salt array element will always be present, even
	 * if no salt was found in the <code>mergedPasswordSalt</code> argument.
	 * </p>
	 * 
	 * @param mergedPasswordSalt
	 *            as generated by <code>mergePasswordAndSalt</code>
	 * 
	 * @return an array, in which the first element is the password and the
	 *         second the salt
	 * 
	 * @throws IllegalArgumentException
	 *             if mergedPasswordSalt is null or empty.
	 */
	protected String mergePasswordAndSalt( String password, Object salt, boolean strict ) {
		if( password == null ){
			password = "";
		}
		if( strict && ( salt != null ) ){
			if( ( salt.toString( ).lastIndexOf( "{" ) != -1 ) || ( salt.toString( ).lastIndexOf( "}" ) != -1 ) ){
				throw new IllegalArgumentException( "Cannot use { or } in salt.toString()" );
			}
		}
		if( ( salt == null ) || "".equals( salt ) ){
			return password;
		}else{
			return password + "{" + salt.toString( ) + "}";
		}
	}

	/**
	 * 混淆码。防止破解。
	 */
	private String defaultSalt;

	/**
	 * 获得混淆码
	 * 
	 * @return
	 */
	public String getDefaultSalt( ) {
		return defaultSalt;
	}

	/**
	 * 设置混淆码
	 * 
	 * @param defaultSalt
	 */
	public void setDefaultSalt( String defaultSalt ) {
		this.defaultSalt = defaultSalt;
	}
	
	
}
